1. Field of the Invention
The present invention relates to a charged particle optical system, a drawing apparatus, and a method of manufacturing an article.
2. Description of the Related Art
Japanese Patent Laid-Open Nos. 2000-164508 and 10-149794 disclose techniques of bringing a grid into proximity to an electrostatic lens to reduce the aberration of the electrostatic lens. With these techniques, a grid used as a mask is disposed to be immersed in the electrostatic field of an electrostatic lens (a grid is disposed at the position at which it influences the electrostatic field of the electrostatic lens) to obtain a negative refractive power, thereby reducing the aberration of an electrostatic lens system.
However, charged particle optical systems according to conventional techniques are incapable of satisfying recently required specifications because they cannot sufficiently reduce aberrations.